Advanced stitch placement with backing shifting

Abstract

A shiftable backing feed and shiftable needle assembly is utilized with a tufting machine having reciprocating needles and gauge parts for seizing or cutting yarns wherein marginal step yarn placement techniques can be utilized in connection with a row of needles to minimize over-sewing needle positioning, and three axis shifting may be employed to optimize stitch locations in the backing fabric.

What is claimed is: 
     
       1. A method of reducing the frequency of oversewing tufts when operating a tufting machine for forming tufted fabrics of the type having:
 a first needle bar and a second needle bar, each having a series of needles mounted transversely across the width of the tufting machine;
 a yarn feed mechanism for feeding a series of yarns to said needles, the yarns being carried by said needles; 
 a needle drive for reciprocating the yarn carrying needles through a backing material; 
 backing feed rolls for feeding the backing material through a tufting zone of the tufting machine; 
 a first shifter to move needles of the first needle bar laterally; 
 a second shifter to move needles of the second needle bar laterally; 
 a series of gauge parts mounted below the tufting zone in a position to engage yarns carried by needles as the needles are reciprocated into the backing material to form tufts of yarns in the backing material; 
 a control system for controlling and synchronizing the first and second shifters, the needle drive, the backing feed rolls, the gauge parts, and a needle plate reciprocation; 
 
 comprising the steps of determining when yarns tufts of yarns caried by the needles of the first needle bar are likely to be oversewn by the needles of the second needle bar, and causing the needles of the second needle bar to be marginally shifted on at least selected reciprocations to lessen over sewing yarn tufts of yarns carried by the needles of the first needle bar. 
 
     
     
       2. The method of  claim 1  wherein the tufting machine further comprises a shifter to move the backing material laterally. 
     
     
       3. The method of  claim 2  wherein the first and second needle bars have a gauge and are staggered to create a composite gauge that is the machine gauge and the tufting machine is operated to create patterns with a sew gauge distinct from the machine gauge. 
     
     
       4. The method of  claim 3  wherein the first needle bar and the second needle bar are longitudinally spaced from each other by a longitudinal offset distance, and a stitch advance to cover the longitudinal offset distance is calculated. 
     
     
       5. The method of  claim 2  wherein the tufting machine is operated to create fabrics of different gauges but otherwise similar appearance from a same pattern. 
     
     
       6. A method of altering the needle penetration locations of a yarn placement pattern for a tufting machine having a first needle bar with a needle gauge and a shifter for laterally positioning and displacing the first needle bar and having a second shifter for laterally positioning and displacing a backing fabric fed through the tufting machine, comprising the steps of inputting a bitmap pattern file for a tufting machine pattern at a first gauge including some cut pile tufts of yarn;
 inputting yarn feed rates, yarn threadup information sufficient to identify a number of different yarns used in the pattern and locations of the different yarns with respect to specific needles, and shifting patterns for the first needle bar and the backing fabric; 
 specifying the gauge at which the tufting machine tufts; 
 specifying a second gauge for tufting the pattern; 
 mapping the location of yarn carrying needles at the second gauge to the pattern at the first gauge based upon lateral displacements of both the first needle bar by the first shifter and the backing fabric by the second shifter; 
 selecting yarns to tuft at the second gauge based upon said mapping. 
 
     
     
       7. The method of  claim 6  wherein the tufting machine further comprises a second laterally shiftable needle bar and mapping locations of yarn carrying needles based upon lateral displacements of the first needlebar, the second needlebar and the backing fabric. 
     
     
       8. The method of  claim 7  wherein the needles of the second needle bar are marginally shifted to minimize over sewing yarn tufts of yarns carried by the needles of the first needle bar. 
     
     
       9. The method of  claim 7  wherein the needles of the first and second needlebars are threaded with a repeating sequence of an odd number of different yarns. 
     
     
       10. The method of  claim 7  wherein the first needle bar and the second needle bar are longitudinally spaced from each other by a longitudinal offset distance and a stitch advance to cover the longitudinal offset distance is calculated as a part of mapping the locations of the yarn carrying needles. 
     
     
       11. A method of reducing the frequency of oversewing tufts when operating a tufting machine for forming tufted fabrics of the type having:
 a first needle bar and a second needle bar longitudinally spaced from each other by a longitudinal offset distance, and each having a series of gauge spaced needles mounted transversely across the tufting machine; 
 a yarn feed mechanism for feeding a series of yarns to said needles, the yarns being carried by said needles; 
 a needle drive for reciprocating the yarn carrying needles through a backing material; 
 backing feed rolls for feeding the backing material through a tufting zone of the tufting machine and a backing shifter to laterally move and position the backing material; 
 a first shifter to move needles of the first needle bar laterally; 
 a second shifter to move needles of the second needle bar laterally; 
 a series of gauge parts mounted below the tufting zone in a position to engage yarns carried by needles as the needles are reciprocated into the backing material to form tufts of yarns in the backing material; 
 a control system for controlling and synchronizing the first, second and backing shifters, the needle drive, the backing feed rolls, the gauge parts, and a needle plate reciprocation; 
 wherein the needles of the first and second needlebars are threaded with a repeating sequence of an odd number of different yarns, and 
 wherein the first and second needle bars have a composite gauge that is the machine gauge and comprising the steps of laterally shifting the backing material in units of the machine gauge between reciprocations of the yarn carrying needles and laterally shifting each of the first and second needlebars in units of their respective needle gauge spacing between reciprocations of the yarn carrying needles. 
 
     
     
       12. The method of  claim 11  wherein the needles of the second needle bar are marginally shifted to minimize over sewing yarn tufts of yarns carried by the needles of the first needle bar. 
     
     
       13. The method of  claim 11  wherein the odd number of different yarns is three different yarns. 
     
     
       14. The method of  claim 11  wherein the tufting machine is operated to create patterns with a sew gauge distinct from the machine gauge. 
     
     
       15. A method of reducing the frequency of oversewing tufts when operating a tufting machine for forming tufted fabrics of the type having:
 a first needle bar and a second needle bar longitudinally spaced from each other by a longitudinal offset distance, and each having a series of gauge spaced needles mounted transversely across the tufting machine; 
 a yarn feed mechanism for feeding a series of yarns to said needles, the yarns being carried by said needles; 
 a needle drive for reciprocating the yarn carrying needles through a backing material; 
 backing feed rolls for feeding the backing material through a tufting zone of the tufting machine and a backing shifter to laterally move and position the backing material; 
 a first shifter to move needles of the first needle bar laterally; 
 a second shifter to move needles of the second needle bar laterally; 
 a series of gauge parts mounted below the tufting zone in a position to engage yarns carried by needles as the needles are reciprocated into the backing material to form tufts of yarns in the backing material; 
 a control system for controlling and synchronizing the first, second and backing shifters, the needle drive, the backing feed rolls, the gauge parts, and a needle plate reciprocation; 
 wherein the first and second needle bars have a composite gauge that is the machine gauge and comprising the steps of laterally shifting the backing material in units of the machine gauge between reciprocations of the yarn carrying needles and laterally shifting each of the first and second needlebars in units of their respective needle gauge spacing between reciprocations of the yarn carrying needles; and 
 
       wherein the shifting of the needlebars is calculated with a stitch advance for an even number of stitches to cover the longitudinal offset distance between the first and second needlebars. 
     
     
       16. The method of  claim 15  wherein the needles of the second needle bar are marginally shifted to minimize over sewing yarn tufts of yarns carried by the needles of the first needle bar. 
     
     
       17. The method of  claim 15  wherein the needles of the first and second needlebars are threaded with a repeating sequence of an odd number of different yarns. 
     
     
       18. The method of  claim 17  wherein the odd number of different yarns is three different yarns. 
     
     
       19. The method of  claim 15  wherein the tufting machine is operated to create patterns with a sew gauge distinct from the machine gauge.